The Section on Molecular Neuroscience studies the molecular mechanisms of chemically coded ionotropic and metabotropic neurotransmission in the nervous system. The ultimate goals of the project are identifying molecular components of synaptic transmission, and how these components are regulated to allow short-term and long-term information to be encoded within postsynaptic neurons and neuroendocrine cells. In 2001-2002, we have made the following advances. 1. 73 genes regulated by PACAP in PC12 cells have been identified by microarray analysis, grouped according to regulation through distinct protein kinase-mediated pathways, and correlated with the dependence on activities of these kinases of several cell physiological responses to PACAP, including neurite extension, cessation of cell proliferation, and expression of functional neurotransmitter traits (Vaudry et al., J. Neurochem., in press, 2002). 2. Bioinformatics tools (pathFinder; the STKE PC12 cell differentiation Connections MAP) have been collaboratively developed that aid in the design and interpretation of cell signaling experiments in PC12 and bovine chromaffin cells. These tools were used to help characterize a cAMP-dependent/PKA-independent pathway regulating gene transcription by PACAP in neuroendocrine cells (Hamelink et al., J. Neurosci. 22, 5310, 2001; Vaudry et al., Science 296, 1648, 2002; Hamelink et al., Ann. N.Y. Acad. Sci., in press, 2002). 3. A PACAP knock-out mouse model has been used to demonstrate the role of this neuropeptide in preventing 'homeostatic fatigue' during metabolic, thermal and ischemic stress (Hamelink et al., Proc. Natl. Acad. Sci. USA 99, 461, 2002; Y. Chen et al., Soc. Neurosci. Abstr. 2002). 4. Combinatorial signaling by PACAP involving the synergistic actions of calcium and cyclic AMP on VIP gene transcription has been mapped to three discrete domains of the VIP gene, a common proximal element responsive to both calcium and cyclic AMP, and upstream and far upstream elements responsive to cyclic AMP and calcium, respectively (C. Hamelink et al., Soc. Neurosci. Abstr. 2002).